Modified lubricating oil



Patented Dec. 5, 1944 UNITE STATES MODIFIED wnarca'rme on.

Herbert G. Freuler, Orinda, Calif., assignor' to Union Oil Company oi California, Los Angeles, Calif., a corporation or California i No Drawing. Application October 21, 1941,

Serial No. 415,955

48 Claims.

This invention relates principally to lubricating oils, but may be extended also to other forms of lubricants such as greases, the so-called liquid greases and thelike. I

This application is a continuation in part of my prior application Serial Number 156,946, filed August 2, 1937.

The object of the invention is to produce lubrieating oils and other lubricants having high film strength, good oiliness characteristics, resistance to oxidation and to corrosion as by inhibiting the development of oxidation and corrosive conditions in the lubricants.

I have discovered that by the addition of minor proportions of oil-soluble metal salts of alkyl esters of thio acids of phosphorus to lubricating oils, with or without the addition of other agents to the oils such as soaps and the like for the purpose of imparting detergent properties or thickening the oils, the resistance of oils to oxidation is greatly improved by what appears to be an inhibiting action on the part of the metal salts of the thiophosphates. Also the tendency to corrosion of metals by reason of the presence of some types of addition agents introduced into compounded oils to impart extreme pressure characteristcs, is inhibited by these metallic derivatives of the phosphorus acids. This may apply to lubrication of gears, internal combustion engines, and other metal parts. Also the mentioned phosphates exert an inhibiting action against the development of conditions which are corrosive to highly corrosion-sensitive hearings in internal combustion engines and the like, such as Diesel engines and high-output aviation engines. For example, some highly refined lubricating oils have a tendency toward the development, apparently by oxidation, of acids corrosive to bearings such as cadmium-silver and copperlead bearings while in use at the high temperatures found in internal combustion engines. Also similar corrosive acids tend to develop in some compounded oils while in use. Examples are oils which contain various detergent soaps now used in Diesel engines and the like. These soaps normally are added to the oils to overcome valve and ring sticking and thelike and to keep the pistons and ring grooves clean. Such soaps include the oil-soluble metal soaps of various carboiwlic acids such as chlorinated and phenylated fatty acids, oil-soluble metal soaps of high molecular weight acids derived from the oxidation of highly parafllnic petroleum fractions such as highly refined lubricating oils, and the like. These soaps, which, may be alkaline earth metal soaps or heavy metal soaps such as calcium, magnesium, barium, zinc, lead, manganese and aluminum soaps, tend sometimes, especially at the elevated temperatures of internal combustion engines, to catalyze oxidation with the formation of acids, possibly carboxylic acids, which are corrosive to the mentioned highly corrosion-sensitive copper-lead and cadmium-silver type.

I have found that by employng minor proportions of the metal thiophosphates of the present invention with these various oils or compounded oils, the tendency toward oxidation and the development of the corrosive conditions is materially inhibited. For example, I may employ in the order of from to 2.0% of various detergent soaps in an oil, and inhibit corrosion otherwise resulting from such soaps, by employing from 0.1% to 1.0% or 2.0% of one of the present metal thiophosphates as an inhibitor. These salts may also be added to compounded oils other than those mentioned. Again, I may add corresponding proportions of one of these metal thiophosphates to a highly refined highly parafiinic mineral lubricating oil and similarly inhibit oxidation and the development of corrosive conditions. This control of corrosion may or may not be the same type of control as that resulting where chlorinated or sulfurized extreme pressure agents are added to lubricants.

My invention therefore resides primarily in the employment in compounded or in uncompounded mineral lubricating oils, of minor proportions of oil-soluble metal salts of the thio acids of phosphorus substituted with organic radicals such as alkyl radicals which tend to render the salt oil-soluble. In addition to the mentioned alkyl groups, other alkyl organic substituents of sufiiciently high molecular weight to render the salts oil-soluble may be employed, such as alkaryl radicals, alkylated cyclic radicals, and the like. Other suitable metals are the alkaline earth metals calcium, magnesium and barium, and the lighter 0f the so-called "heavy metals" such as zinc and aluminum, and other heavy metals such as lead, mercury, copper, manganese, iron, tin, bismuth, and thorium. For example, for the purpose of producing a most desirable extreme pressure agent I have employed zinc salts of octyl and di-octyl thiophosphates, and on an average about 1.0% thereof based on the oil in the case of lubricating oils, or total content if a grease, has been found very satisfactory. Other alkyls containing less than ten carbon atoms may be employed as substituents, so long as these render the salts oil-soluble. Examples are the alcoholscontaining such groups as the in use, and are good inhibitors or 'retarders oi corrosive conditions which result from the use of corrosive oiliness agents and the like containing halogens and corrosive sulfur, for example. The-zinc salts have been found very desirab in the preparation of extreme pressure agen and calcium and barium salts are very desirable as oxidation and corrosion retarders.

thiophosphates, octyl thiophosphate has been prepared readily by'adding powdered phosphorus pentasuliide to octyl alcohol in a glass or ceramic container in the proportion oi one gram mol Instead of indicated alkyl groups as solubiliza ny-to four grain mols, respectively, and agitating ing constituents, allrylated phenyl, naphthalene and antlu'acene groups may be employed, cluding kindred alkylated aryl groups such as amyl; substituted phenol groups or octyl-substituted phenol or naphthyl or cresyl groups. 'Also alkylated cyclic groups may be employed such as obtained by the use of alkylated cyclic alcohols. All these alkyl groups, however, are to contain less than ten carbon atoms per group.

Thus, in all instances, the alkyl groups will contain preferably from 4 or 5 to 8 or 9 carbon atoms per group, whether these alkyls are attached to aryl groups or not.

A specific example of this invention which is the mixture at temperatures of 250 F. to 300 1'. until the phosphorus pentasuliide has been dis-. solved. -This liquid product is then treated similar temperatures with an excess of a pow dered metal or metallic'oxide to 01m the corresponding metal derivative. For example, in order to prepare the zinc'o'ctyl thiophosphate, the material resulting from the treatment of octyl al-' cohol with phosphorus pentasulflde is agitated with powdered zinc or zinc oxide until no moreof the metallic compound is dissolved.

Similar preparations can be made with other metals, although in most cases it is preferable to use the metallic oxide. The metallic derivaparticularly valuable as a high film strength amrwrtlves of octyl thioph phate and similar thio-' oiliness agent, and which also imparts some oxi-- dation inhibiting value to oils compounded therewith, is zinc di-octyl thiophosphate. The corresponding lead salt is also useful. when zinc octyl thiophosphate (produced from zinc oxide and the reaction product of octyl alcohol and phos- 1 phorus pentasulflde as herein described) was used in an amount approximating 1.0% as an addition agent to lubricating oils, the load which the oil was capable of withstanding when tested-40 by the well known Timken lubricant tester at 800 R. P. M. (described in S. A. E. Journal, vol. 28, 1931, pages 53-60) was increased irom seven pounds without the agent to forty-five pounds when employing the agent. In addition to this film strength increase, the oil is made much more resistant to oxidation than in its original state.

, or zinc octyl thiophosphate, other indicated metal salts may be employed, d likewise other indicated allwl thiophosphates of such metals may he used. Examples of such other metals are alu= minum, calcium, gnesium and others herein indicated.

In referring to the content or l.l% of the salt 65 in the lubricating oil, it is not intended to Ii-Ii vey the idea that this amount is critical. Varying proportions may be employed in mineral lubricating oils between any lower range suihcient or stabilization, or oxidation control, for example, 0.1%, up .to a figure such as beyond phosphates are easily soluble in mineral oils of" .both western and eastern types (naphthenic and to produce the desired increased film strength,

which added material produces no appreciable increased efiect. For example, 16% of lead or zinc dioctyl mic-phosphate in an appropriate paraiiinic) andthe oil solutions are therefore readily prepared by mere introduction of the salt and subsequent mild agitation. Theterm "octyl thiophosphate used in this disclosure may refer to either the dior the mono-octyl thiophosphate, although it is the di-octyl thiophosphate which is the principal product of the abov preparatlon. This is usually true of the other phosphates.

The specific material produced by the method above described showed rapid reaction with evolution of hydrogen sulfide when the temperature reached 250 F. The phosphorus pentasulfide had all gone into solution, that is had entered into chemical combination. in about two hours. This material analyzed 18.1% sulfur and 9.3% phosphorus. This indicated a following tion:

on S=1 --O.C|;Hu

I .CsEfl There is some evidence ofthe presence of a mono-octyl thiophosphate which would have the formula:

SH 7 S=I!O.CBH11 B Other possible combinations are:

H l 0.0m" s=l'-s.CiH|r and s'= 0.0m"

' .CrHrr 311111 The product produced as above described may he a mixture of all of these esters. The metal 'salts of these thiophosphates produced by the method above described were prepared by mixing the described ester with an excess of the oxides of the respective metals, such; as zinc, lead, copproduct oi the per, manganese, iron and tin. and allowing the resultant mixtures to stand overnight at about 250 F. Upon decanting and filtering, light colored viscous liquids were obtained. except in the case of iron and manganese where the liquids were dark.

These various metal salts of the thiophosphate esters were blended in a highly solvent refined highly paraflinic western lubricating oil in the amount of about 1.0% of the ester to 99% of the oil. and tested on the well known Timken tester for extreme pressure characteristics. In each instance an increase in the film strength was noted as measured by the increase in load supported over that supported by the same oil untreated. Similar results were obtained by testing each of the materials in'the same proportion in the same oil upon the S. A. E. extreme pressure lubricants tester.

Each of the above described blends was also subjected to a corrosion test and found to show definite inhibition of corrosion to metals, although some exhibited greater corrosion inhibitingpro'perties than others. Similarly each blend was tested and found to possess distinct oxidation inhibiting properties in the oil at elevated temperatures.

The thio-salts previously described are adequately soluble in mineral lubricating oils, and are used according to this invention to control the sticking of piston rings and the like and also to stabilize the oil and to control other oxidation efiects and tendencies to develop corrosive conditions in lubricating oils when used in internal combustion engines and the like, especially under the high temperature conditions of severe accuse service engines such as Diesel engines. -Calcium and zinc dioctyl phosphates are good examples. Around 0.5% to 1.0% probably will be commonly used for lubricating oils although proportions between about 0.3% and 2.0% will be in order and possibly for some uses as low as 0.1% or 0.2 and perhaps as high as 3% or 4%. This may depend on oil-solubility; lower molecular weight alkyl substituents imparting less solubility, but being more active and therefore requiring smaller proportions.

I claim: f

1. A. composition of matter comprising a hydrocarbon oil subject to deterioration at elevated temperature and a polyvalent metal salt of a suliur containing substituted acid. of phosphorus having an organic substituent therein, said salt being present in an amount suilicient substam tially to inhibit said deterioration.

2. A composition as set forth in claim 1, in which the salt is a lead salt.

3. A composition as set forth in claim 1, in which the salt is a zinc salt.

a. A composition as set forth in claim 1, in which the salt is an aluminum salt.

' 5. A composition of matter comprising a hydrocarbon oil subject to deterioration at elevated temperatures and a polyvalent metal salt of a sulfur containing substituted acid of pentavalent phosphorus having an organic substituent therein, said salt being present in an amount sufiicient substantially to inhibit said deterioration.

6. A composition as set forth in claim 5, in which the salt is a lead salt. 1

7. A composition as set forth in claim 5, in which the salt is a zinc salt.

3. A composition as set forth in claim 5, in which the salt is an aluminum salt.

W 3 9. A composition of matter comprising a hydrocarbon oil subject to deterioration in the presence present in an amount suflicient substantially to inhibit said deterioration.

10. A composition of matter comprising a hydrocarbon oil subject to deterioration in the presence of oxygen and a lead salt of a thioester of phosphoric acid, said salt being present in an amount sufllcient substantially to inhibit said deterioration.

11. A composition as set forth in claim 9, in which the salt is a zinc salt.

12; A composition asset forth in claim 9, in

which the salt is an aluminum salt.

13. A composition of matter comprising a hydrocarbon oil subject to deterioration in the presence of oxygen and a polyvalent metal salt of an ester of a thiophosphoric acid, said salt being present in an amount sufficient substantially to inhibit said deterioration.

14. A composition of matter comprising a hydrocarbon oil subject to deterioration in' the presence of oxygen and a lead salt of an ester of a thiophosphoric acid, said salt being present in an amount suflicient substantially to inhibit said deterioration.

15. A composition as set forth in claim 13, in which the salt is a zinc salt.

16. A composition as set forth in claim 13, in whichthe salt is an aluminum salt.

17. A composition of matter comprising a hydrocarbon oil subject to deterioration in the presence of oxygen and a polyvalent metal salt of a thioester of a thioacid of phosphorus, said salt being present in an amount sufiicient sub stantially to inhibit said deterioration.

18. A composition asset forth in claim 1'7, in which the salt is a lead salt.

19. A composition as set forth in claim 1'7, in Which the salt is a zinc salt.

20. A composition as set forth in claim 17, in which the salt is an aluminum salt.

21. A composition of matter comprising a hydrocarbon oil subject to deterioration in the presence of oxygen and a polyvalent metal salt of a thioester of a thiophosphoric acid, said salt being present in an amount suflicient substantially to inhibit said deterioration.

22. A composition comprising a hydrocarbon oil subject to deterioration at elevated tempera ture and an oil soluble polyvalent metal salt of an alkyl thiophosphate, said salt being present in an amount sufficient substantially to inhibit said deterioration.

23. A composition as set forth in claim 22, in which the salt is a lead salt in an amount of from approximately 0.1% to approximately 4% based on the weight of the oil.

24. A composition as set forth in claim 22, in which the salt is a zinc salt in an amount of from approximately 0.1% to approximately 4% based on the weight of the oil.

25. A composition as set forth in claim 22, in which the salt is an aluminum salt in an amount of from approximately 0.1% to approximately 4% based on the weight of the oil.

26. A composition comprising a hydrocarbon oil subject to deterioration at elevated temperature and an oil soluble metal salt of an alkyl thiophosphate in which the alkyl group contains less than ten carbon atoms, said salt being present in an amount sufflcient substantially to inhibit said deterioration.

2'1. A composition as set forth in claim 26, in which the salt is alead salt.

28. A composition as set forth in claim 26, in which the salt is a zinc salt.

29. A composition as set forth in claim v26, in which the salt is an aluminum salt.

30. A composition of matter comprising a hydrocarbon oil subject to deterioration at elevated temperature and an oil soluble metal salt of a sulfur containing substituted acid of phosphorus having at least one organicsubstituent of eight carbon atoms therein in an amount sufilcient substantially to inhibit said deterioration.

31. A composition as set iorth'in claim 30, in which the salt is a lead salt. a r

32. A composition as set forth in claim 30, in which the salt is a zinc salt.

33. A composition as set forth in claim 30, in which the salt is an aluminum salt.

34. A composition comprising a hydrocarbon oil subject to deterioration at elevated temperatures and an oil-soluble polyvalent metal salt of an octyl thiophosphate, said salt being present in an amount sumcient substantially to inhibit said deterioration.

35. A composition as set forth in claim 34, in which the salt is a lead salt.

.42. A lubricating oil containing a constituent corrosive to metal of the class consisting of sulfur. chlorine. sulfurized bodies, halogenated compounds. and metal corrosive organic compounds containing sulfur and halogens, and an oil-soluble polyvalent metal salt of a sultur containing subpolyvalent metal salt is obtained by reacting phosphorus pentasulfide with an alcohol.

44. A composition as set forth in claim, 5, in

which the salt is a lead salt and the sulfur con taming acid oi pentavalent phosphorus employed to produce the polyvalent metal salt is obtained.

by reacting phosphorus pentasulfide with an sl-= cohol.

36. A composition as set forth in claim 34, in v which the salt is a zinc salt.

37. A composition of matter comprising a hydrocarbon oil subject to deterioration at elevated which the salt is an aluminum salt.

41. A. composition comprising a hydrocarbon oil subject to deterioration at elevated temperatures and an oil-soluble polyvalent metal salt of a di-octyl thiophosphate, said salt being present in an amount suficient substantially to inhibit said deterioration.

45. A composition as set forth inclaimfb, in which the salt is a zinc salt and the suliur containing acid of pentavalent phosphorus employed to produce the polyvalent metal salt is -obtained by reacting phosphorus pentasulfide with an alcohol.

' 46. A composition as set forth in claim 5;, in which the salt is an aluminum salt and the sulfur containing acid of pentavalent phosphorus employed to produce the polyvalent metal salt is obtained by reacting phosphorus peritasulilde with an alcohol.

47. A composition of matter as set iorth in claim 5, in which the sulfur containing acid of pentavalent phosphorus employed to produce the polyvalent metal salt'is obtained by reacting phosphorus pentasulflde with an aliphatic alcohol.

48. A composition of matter as set forth in claim 5, in which the sulfur containing .acid oi pentavalent phosphorus employed to produce the polyvalent metal salt is obtained by "reacting phosphorus pentasulfide with an octyl alcohol.

HERBERT C.- FREULER.

forth in. 

